As protection of use of a terminal and system, and of data and contents, a determination of whether a user is legitimate depending on whether a password set and registered in advance, and a password inputted with keys when the terminal is used, and the like, coincide, is most common.
However, with this password method, there is a problem in that while a meaninglessly arranged password is easily forgotten and inconvenient, one's own or a family member's birthday, telephone number, or the like, is not easily forgotten, but is easily leaked or guessed at. In response to this, a graphic password method, which is an individual authentication technique using graphic data which is easy to remember in comparison with a password, has been proposed.
As related technology relating to a graphic password, in Japanese Unexamined Patent Application JP-A 60-171560 (1985), by carrying out a grid display in a specified portion of a display, or the like, and inputting a graphic as a password by indicating the grid display with a light pen, or the like, the password is easy for a user to remember, and upgraded security is obtained.
Also, in Japanese Unexamined Patent Application JP-A 61-142835 (1986), an authentication method is proposed whereby, by carrying out an authentication depending on whether a two-dimensional coordinate point registered in advance as a password by a user is included within a region enclosed by a closed curve indicated by two-dimensional graphic information inputted by the user, as well as the user being able to remember the password easily, and the authentication operation being easy, it is unlikely that the password will be detected by another person.
In Japanese Unexamined Patent Application JP-A 2004-213117, an authentication system is disclosed wherein, by inputting a random number positioned on crisscross lines including a graphic which is to be a password, in a matrix display in which a plurality of differing graphics are disposed, and authenticating depending on whether the random number coincides with a random number corresponding to a graphic correlated to a user ID, it is possible for a user, simply by memorizing an easily remembered graphic, to easily acquire a one-time password (a disposable password which is used once only) for him or herself only, and it is possible to prevent theft by peeping, or the like.
The heretofore described graphic password methods are broadly divided into two, the kind of method shown in JP-A 60-171560 which has a graphic trajectory as a password, and the kind of method shown in JP-A 2004-213117 which has an operation and information when selecting a graphic as a password. JP-A 61-142835 is a password method intermediate between the two.
At present, as individual authentication is required in a variety of life situations, and there are many occasions to input a password, from the point of view of preventing an information leak and protecting information, it is necessary for one individual to remember a large number of passwords. Consequently, even in the event that a portable terminal is accompanied by a secret function, because it is troublesome to have to remember a password, there is a tendency for the secret function not to be used when the effect of an information leak is small.
In the case of the heretofore described graphic password method which has a graphic trajectory as a password, there is a problem regarding a recognition accuracy element, whether it should be of an extent of character recognition of a password outputted by means of a graphic trajectory—whether a circle has been inputted, whether a triangle has been inputted, and the like—or whether it should go so far as to recognize whether the user is carrying out the operation in person. The recognition accuracy element varies depending on the usage situation. For example, with a mobile telephone for personal use, there are many situations in which a password is inputted while walking, and when considering the input of a graphic password in this kind of situation, it can be considered that unless the details can be easily remembered, they are not suitable for making into a password. In this kind of situation, it can be envisaged that even a case of incorporating “the size of the graphic” into the password may give rise to a situation wherein the user cannot unlock the password in person.
Meanwhile, in the event that a password outputted by means of a graphic trajectory is made a simple one wherein a circle is inputted, a triangle is inputted, or the like, although the user can easily remember the password in person, when considering a situation wherein the password is inputted while moving where a large number of strangers exist in the periphery, there is a possibility that cases of a password leak will increase due to the graphic password being peeped at by another person during the input operation.